Heat exchanger tube



Jan- 1, 19 c. B. CORAGGIOSO 3,071,159

HEAT EXCHANGER TUBE Filed April 15, 1959 3,071,159 HEAT EXQHANGER TUBE (Torrado Bonn Qoraggioso, Via Friuli 82, Milan, Italy Fiied Apr. 15, 1959, fier. No. 806,635 Claims priority, appiication Italy Apr. 19, 1958 2 Claims. (Cl. 13838) The present invention relates to a heat exchanger intended for use in a transfer of heat between two fluids separated by a conductor wall, and more particularly by the wall of a metal tube, for the recovery of heat given off by hot liquids or gasses, and this heat exchanger is intended to improve the cofficient of thermic exchange between the fluid contained in the tube and the fluid external to this same tube. The higher the percentage of fluid contained in the tube which is in close contact with the internal wall of the tube, the higher will be the cofficient of thermic exchange. According to the present invention there is obtained a higher percentage of fluid in contact with the internal wall of the tube by inserting into it a member which forces the fluid to flow along close to this wall.

According to the invention the heat exchanger is characterised by the distinctive feature that it consists of an elongated body, fitted so as to give an annular channel or passage between it and the wall of the tube, and around this body there are one or several members which impart a turbulent flow to the fluid.

Under this arrangement the fluid which passes along the tube is forced to occupy the space left free by the inserted body and thus makes intimate contact with the wall of the tube which is the medium for the exchange of heat. In addition, because of the presence of a component or components fixed around the body the fluid receives a swirling movement which improves further contact between this fluid and the internal wall of the tube.

The invention will be better understood from the following detailed description given solely under the head of one example, and therefore not restrictive, of certain forms of realisation, with reference to the attached drawings in which:

FIG. 1 is a side elevation, in section, of a heat exchanger according to the invention;

FIG. 2 is an end view of the heat exchange of FIG. 1;

FIG. 3 is a view in side elevation, of two combined components intended for use in a heat exchanger according to the invention;

FIG. 4 is a view in sectional side elevation, of a variant in the heat exchanger with reference to the form of realisation shown in FIG. 1;

FIG. 5 is a sectional side view, split into parts, of another variant of the heat exchanger according to the invention;

FIG. 6 is a sectional side view of another variant of the heat exchanger according to the invention.

Examining first of all the FIGS. 1 and 2, these represent a heat exchanger composed of a tube 1 fitted between the sides 2 and 3 of a boiler. A hollow cylindrical component of elongated form 4 is fitted co-axially into the tube. The end of this component facing against the flow of the fluid indicated by arrows, is closed by a cap 5. The component 5 rests on small supports 6 attached to it and these hold it at an equal distance from the internal wall of the tube 1. Around the component 4 a rod 7 is wound helically. Inside the space 8 left free between the inside Wall of the tube 1 and the component carrying the windings of the rod 7, combustion gases travel passing to the chimney, and these gases being in close contact with the Wall of the tube 1 and being forced by the screw rod 7 to alter position according to a swirling helical EE'ZLHQ Patented Jan. 1, 1953 movement, effect a high heat exchange with the wall of the said tube itself.

In FIG. 3 the body inserted into the tube consists of two components 4a and 4b, conjoined, and one of these namely 4b is fitted with a streamlined terminal cap 5. Both of these two components have a rod 7 wound around them helically. They are maintained firmly joined together by means of one or several clamps 9 suitably fixed to the component 4a and penetrating by means of folded extremities into an opening made in the other component 4b. This hooking arrangement between the components 4a and 4b is particularly useful for facilitat ing extraction.

FIG. 4- represents a component 4 fitted with an extractor lti which, when required serves to draw out the component 4 from the tube 1. This form of realisation will be with advantage employed in those instances where, for various reasons as for example to reduce frictional losses and to assist the passage of the fluid, the length of the component 4 is to be realised as less than that of the heat exchanger tube.

FIG. 5 represents a form of realisation of the invention in which the body inserted inside the tube 1 consists of three lengths or pieces of decreasing volume 4x, 4y and dz, joined together by fixing clamps 9 and 9 similar to clamp 3 in FIG. 3. Such a form of realisation can be advantageously adopted in those instances where it might be considered useful to obtain an increase in the transitional velocity of the fluid from its entrance into the heat exchanger tube to its exit from the same tube.

As well as being of different diameters, these three lengths could also be of different shape and. extent and even of different materials in order to satisfy better particular requirements.

FIG. 6 represents a form of realisation in which the same purpose practically is obtained as in FIG. 5, by constructing the component 4 in the shape of a cone.

The cross-section of the drawn metal rod wound helically will be preferably between and of the crosssection of the elongated body. If the drawn metal rod is wound as a screw the pitch of the screw should lie between 2 and 20 times the depth of the drawn rod itself. The pitch of the screw may be altered on the length of the same component either to meet the successive conditions of the state of the fluid or for certain technicaleconomic reasons.

The geometrical dimensions of the component and their proportions to each other are determined either in order to reach a given value of the coefficient of heat or else to adapt itself to the conditions of the characteristics of the fluid in movement, its speed and the temperature in play.

Although only certain forms of realisation of the invention have been described and represented, it is evident that many variants and modifications may be advanced without departing from the field covered by the invention itself.

What I claim is:

1. A heat exchanger tube having inside thereof and concentrically therewith a tubular body closed at one end, said body have a cross-sectional area which is substantially large with respect to the cross-sectional area. of said tube so as to leave a tubular passage between said body and the interior surface of said tube, and at least one relatively longitudinally narrow elongated member wound spirally on said body along its length with the turns of said member substantially Widely spaced from each other, the spiral crests of said elongated member being spaced from the interior surface of said tube to provide a tubular passage for the restricted but substantial flow of fluid therethrough.

2. A heat exchanger tube as set forth in claim 1 wherein said elongated member is a wire.

References Cited in the file of this patent UNITED STATES PATENTS Wilkinson Aug. 18, 1874 Dean Jan, 18, 1876 Kemble Apr. 30, 1895 Seyforth Oct. 30, 1900 10 Steinhart Apr. 18, 1905 Musgrave Nov. 21, 1922 Powel Oct. 2, 1923 McGrath Nov. 24, 1931 Woodson Jan. 19, 1937 Blauvelt Sept. 24, 1940 Hamlink Nov. 11, 1941 Arvins et al Oct. 10, 1944 Moseley Sept. 2, 1952 Dowell July 24, 1956 FOREIGN PATENTS France Oct. 21, 1921 Great Britain Nov. 3, 1943 

1. A HEAT EXCHANGER TUBE HAVING INSIDE THEREOF AND CONCENTRICALLY THEREWITH A TUBULAR BODY CLOSED AT ONE END, SAID BODY HAVE A CROSS-SECTIONAL AREA WHICH IS SUBSTANTIALLY LARGE WITH RESPECT TO THE CROSS-SECTIONAL AREA OF SAID TUBE SO AS TO LEAVE A TUBULAR PASSAGE BETWEEN SAID BODY AND THE INTERIOR SURFACE OF SAID TUBE, AND AT LEAST ONE RELATIVELY LONGITUDINALLY NARROW ELONGATED MEMBER WOUND SPIRALLY ON SAID BODY ALONG ITS LENGTH WITH THE TURNS OF SAID MEMBER SUBSTANTIALLY WIDELY SPACED FROM EACH OTHER, THE SPIRAL CRESTS OF SAID ELONGATED MEMBER BEING SPACED FROM THE INTERIOR SURFACE OF SAID TUBE TO PROVIDE A TUBULAR PASSAGE FOR THE RESTRICTED BUT SUBSTANTIAL FLOW OF FLUID THERETHROUGH. 